I can't remember whether PP 2012 has these options. It may not. But just in case it does: Go to Render>Render Settings> Preview (tab). At the bottom right, there's a slider called "Preview Resolution". Lowering that may help. I have 12 gigs of RAM, but my vidcard isn't OpenGL optimized, and I sometimes have trouble with the display. I have my preview textures maxed at 512. If you don't have those options, you may have to resort to creating a reduced set of textures yourself.

But sometimes the sheer amount of geometry can slow things down, and morphs count, even when not used. First, check out the scene in "Smooth Lined" document mode. Are there any areas of very dense mesh? If there are, that may give you an idea of what you might need to optimize. Next, look at the terradome figure -- how many morphs have you loaded on that thing? Remove all the ones you aren't using. That may help too.

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PoserPro 2014, PS CS5.5 Ext, Nikon D300. Win 8, i7-4770 @ 3.4 GHz, AMD Radeon 8570, 12 GB RAM.